Midterm

Question 1

Linux Command:

• make a new directory
• list files in current directory
• change directory
• display content of file to terminal

Answer 1

• make a new directory: mkdir
• list files in current directory: ls
• change directory: cd
• display content of file to terminal: cat

Question 2

What do you need in the declaration of an array?

Answer 2

1. Type of elements
2. Name of array
3. Size of array

type name[SIZE];

Question 3

How do you initialise an array?

Answer 3

specify 1+ values inside { }

int nums[3] = {1, 2, 3};

Question 4

How do you access a specific index of an array?

Answer 4

arr[index]

Question 5

Conditional statements

Answer 5

manipulate control flow of program based on the results of BOOLEAN expressions

Question 6

While loops

Answer 6

As long as (condition) is met, do (thing)

while(x > 0) {

{

always initialize conditions outside of loop

Question 7

For loops

Answer 7

do (thing) for (number) times

for (int x = 0; x < 10; x += 1) {

}

Question 8

Functions

What are some important features?

Answer 8

a chunk of code that does something

FEATURES: parameters, argument, declaration, definition, body, return type

Question 9

What is the difference between a function declaration and a function definition?

Answer 9

DECLARATION: tells the compiler about the existence of a function and its parameters

DEFINITION: provides the implementation of the function

Question 10

What do we need for file i/o?

Answer 10

1. FILE: named collection of data stored in memory
2. STREAM: way of reading from and writing to files in a program -> potentially infinite sequence of data

Question 11

Steps to read from a file

What’s the numonic?

Answer 11

ORC

OPEN the file: connect a filestream to file
READ from file: using cin&raquo_space;
CLOSE: clean up

Question 12

What operators can we use to read in information from a file?

Answer 12

1. Read the next number in the file (until whitespace)
   int num;
   cin&raquo_space; num;
2. Read a whole line (until newline character: \n), when you care about whitespace
   char next_char;
   infile.get(next_char);

Question 13

What is a pointer?

Answer 13

a variable that stores the ADDRESS of another variable

Pointers enable pass-by reference: function can modify variables outside its scope via pointers to those variables

Question 14

If we want to modify variables, should we pass them by value or reference?

Answer 14

pass by REFERENCE

any modifications happen to the actual variable (changed throughout the code) not the copy

Question 15

What is pass by value?

Answer 15

pass by value: copy of the variable gets passed into function

Question 16

What is pass by reference?

Answer 16

pass by reference: pass variable’s ADDRESS in memory

we have direct access to the original variable, not a copy

Question 17

*

Answer 17

1. DEREFERENCE: access variable itself
2. DECLARE pointer

Question 18

&

Answer 18

ADDRESS of a variable

Question 19

What is the heap?

Answer 19

• a place to store dynamic memory
• don’t need to know the size
• Allocate using new and delete
• Use VALGRIND to check freed all heap memory

Question 20

What must we do when using the HEAP?

Answer 20

• use POINTERS (ie. pointer in the stack points to the array in the heap)
• allocate memory using NEW
• free memory using DELETE

Car *car_array = new Car[3];

Question 21

How can we check that we have freed all of our heap memory?

Answer 21

use valgrind

Question 22

What is a struct?

Answer 22

package different types of data

Question 23

What are the components of a struct definition?

Answer 23

1. struct keyword
2. Name (capital)
3. Member declarations inside { }
4. Semicolon after { };

Question 24

Are structs passed by value or reference?

Answer 24

Structs are passed by value

Question 25

When do you use dot operator (.) when do you use arrow (-->)?

Answer 25

ARROW: when you have a POINTER to a struct and you want to access one of its members Person *p = new Person; p-->name = (* p).name DOT: access a member of a normal struct instance Person p1 = {"Alice", 25} p1.age = 25

Question 26

int main (argc, char * argv [ ])

Answer 26

argc: # command line arguments argv[ ]: array of strings containing command line arguments

Question 27

Binary --> decimal

Answer 27

1 0 1 0 1*2^3. 0*2^2. 1*2^1. 0*2^0 2^3 + 0 + 2^1 + 0 = 8 + 2 = 10

Question 28

Decimal --> binary

Answer 28

128 64 32 16. 8 4 2 1 0. 1 0. 0. 1 0 1 1 75 = 64 + 8 + 2 + 1 75 - 64 = 11 - 8 = 3 - 2 = 1 - 1 = 0

Question 29

Difference between an int & float

Answer 29

int: no decimal float: has decimal component

Question 30

How would you write this if array was an array pointer? arr[3] = 10

Answer 30

*(arr + 3) = 10

Question 31

How would the syntax differ between a car array on the stack vs heap?

Answer 31

Car car_array[10]; Car *car_heap_array = new Car[10];

Question 32

big O time complexity

Answer 32

worst behavior of an algorithm as input size grows O(1) < O(logn) < O(n) < O(n logn) < O(n^2) < O(2^n)

Question 33

Time Complexity vs Space Complexity

Answer 33

Time Complexity: how long it takes to run a program Space Complexity: how much space (memory) a program uses

Question 34

Scope of variables

Answer 34

Variables are only valid in the block in which they are declared

Question 34

Scope of variables

Answer 34

Variables are only valid in the block in which they are declared Variable names can only be used once within its scope

Question 35

What is a global variables in C++?

Answer 35

can be accessed by any function reduce flexibility (cannot re-use the name)

Question 36

Why do we need pointers?

Answer 36

PASS BY REFERENCE * Instead of passing a copy of variable into a function, we pass adress in memory * Any modifications will change the actual variable PASS BY VALUE * Copy variable gets passed

Question 37

What is recursion

Answer 37

Something is defined in terms of iteself (recursive function calls itself)

Question 38

How to design a recursive function?

Answer 38

* **Base case(s)**: case that we know the answer * **Recursive case(s):** one step closer to base case

Question 39

Class vs object

Answer 39

CLASS * blueprint (describes the components of a thing) * Outline how to interact with that ting OBJECT * Has specific values for each component

Question 40

Classes: getters & setters

Answer 40

* **getters**: retrieve the value of a class's private fields * **setters**: change the value of a class's private fields

Question 41

Classes: deconstructor ~Name( );

Answer 41

Only need a deconstructor when we have DYNAMIC memory Called automatically at the end of a progoroam

Question 42

Where are class methods defined?

Answer 42

In the .cpp file: **FUNCTIONS** ie: getters & setters, functions

Question 43

Vectors

Answer 43

Array that can **grow & shrink** under hood: when size=capacity, create a new array 2x as big, copy values, destroy origanal one

Question 44

Vector operations * size(): * at(index): * push_back(value): * pop_back(): * instert(index, value): * erase(index):

Answer 44

* **size()**: size of the vector * **at(index)**: find the value at a specified index * **push_back(value)**: insert new value at end * **pop_back()**: delete last value in the vector * **instert(index, value)**: insert value at specified index * **erase(index)**: erase value at specified index | Call function: vendors.size()

Question 45

What do classes have?

Answer 45

Class **declaration** (.h file) * public fields * private fields (METHODS: getters & setters) **Constructor** (automatically called when an object of a class is initialized) **Deconstructor** (only with DYNAMIC memory)

Question 46

Card constructor example

Answer 46

Question 47

Card getter example

Answer 47

Question 48

Player setter example

Answer 48

| player1.setPerstige(buy->getPrestige());

Question 49

Player destructor example

Answer 49

Question 50

What is time complexity?

Answer 50

O(1)

Question 51

What is time complexity?

Answer 51

O(n)

Question 52

What is time complexity?

Answer 52

O(2^n)

Question 53

What is time complexity?

Answer 53

O(nlogn)

Question 54

What is a binary search tree?

Answer 54

cut down complexity from O(n) to O(logn) Every value on left < right